Those swarms are likely just days away, and the Columbia Borough Police Department probably will soon announce that the streetlights on the Columbia-Wrightsville bridge over the river are being shut off to dissuade the mayflies from gathering there.
MORE:
https://www.pennlive.com/life/2019/06/are-mayflies-about-to-swarm-the-susquehanna-once-again.html
Columbia Spy 